TRAN_SETUP_PKT(9E) Driver Entry Points TRAN_SETUP_PKT(9E)

tran_setup_pkt, tran_teardown_pkt, tran_pkt_constructor, tran_pkt_destructor - SCSI HBA packet allocation and deallocation

#include <sys/scsi/scsi.h>
int prefix_tran_setup_pkt(struct scsi_pkt *pkt,
     int (*callback) (caddr_t), caddr_t arg);

void prefix_tran_teardown_pkt(struct scsi_pkt *pkt);

int prefix_tran_pkt_constructor(struct scsi_pkt *pkt,
     scsi_hba_tran_t *tranp, int kmflags);

void prefix_tran_pkt_destructor(struct scsi_pkt *pkt,
     struct scsi_hba_tran_t *tranp);

illumos architecture specific (illumos DDI).

pkt
Pointer to the scsi_pkt(9S) structure.

flags

Flags for associating DMA resources with the packet.

callback

Pointer to either NULL_FUNC or SLEEP_FUNC.

arg

Always NULL.

kmflags

Either KM_SLEEP or KM_NOSLEEP.

The tran_setup_pkt() and tran_teardown_pkt() vectors in the scsi_hba_tran(9S) structure are alternatives to the tran_init_pkt() and tran_destroy_pkt() entry points. They are initialized during the HBA driver's attach(9E) and they are used when a target driver calls scsi_init_pkt(9F) and scsi_destroy_pkt(9F).

The tran_setup_pkt() vector is the entry point into the HBA which is used to initialize HBA specific information in a scsi_pkt structure on behalf of a SCSI target driver. All fields documented in scsi_pkt(9S) are initialized.

If the HBA driver chose not to preallocate memory for pkt_cdbp and/or pkt_scbp, it must allocate the requested memory at this time and point pkt_cdbp and pkt_scbp to the allocated memory.

An HBA driver which provides a tran_setup_pkt entry point inspects the pkt_numcookies and pkt_cookies fields at tran_start time to set up the transfer. If pkt_numcookies is zero, there are no DMA resources associated with this packet. If pkt_numcookies is not zero, it indicates the number of DMA cookies that pkt_cookies points to.

The pkt_tgtlen field contains the length of the packet private area pointed to by pkt_private, allocated on behalf of the SCSI target driver.

The pkt_scblen field contains the length of the SCSI status completion block pointed to by pkt_scbp. If the status length is greater than or equal to sizeof (struct scsi_arq_status) and the auto-rqsense capability has been set, automatic request sense (ARS) is enabled for this packet. If the status length is less than sizeof (struct scsi_arq_status), automatic request sense should be disabled for this pkt if the HBA driver is capable of disabling ARQ on a per-packet basis.

The pkt_cdblen field contains the length of the SCSI command descriptor block.

The callback argument indicates what the allocator routines should do when resources are not available:

NULL_FUNC

Do not wait for resources. Return -1 when resources are not available.

SLEEP_FUNC

Wait indefinitely for resources.

The tran_teardown_pkt() is the entry point into the HBA that must free all of the resources that were allocated to the scsi_pkt(9S) structure during tran_setup_pkt().

When using tran_pkt_setup() and tran_pkt_teardown(), tran_pkt_constructor() and tran_pkt_destructor() are additional optional entry points that perform the actions of a constructor and destructor. The constructor is called after the following fields in the scsi_pkt structure have been initialized:
o
pkt_address
o
pkt_ha_private
o
pkt_cdbp
o
pkt_private
o
pkt_scbp
o
pkt_cdblen
o
pkt_tgtlen
o
pkt_scblen

Allocating and freeing a DMA handle are examples of something that could be done in the constructor and destructor. See kmem_cache_create(9F) for additional restrictions on what actions can be performed in a constructor and destructor.

HBA drivers that implement tran_setup_pkt() must signal scsi_pkt(9S) completion by calling scsi_hba_pkt_comp(9F). Direct use of the scsi_pkt pkt_comp field is not permitted and results in undefined behavior.

tran_setup_pkt() must return zero on success, and -1 on failure.

attach(9E), tran_sync_pkt(9E), bioerror(9F), ddi_dma_buf_bind_handle(9F), kmem_cache_create(9F), scsi_alloc_consistent_buf(9F), scsi_destroy_pkt(9F), scsi_hba_attach(9F), scsi_hba_pkt_alloc(9F), scsi_hba_pkt_comp(9F), scsi_hba_pkt_free(9F), scsi_init_pkt(9F), buf(9S), scsi_address(9S), scsi_hba_tran(9S), scsi_pkt(9S)

Writing Device Drivers

July 31, 2021 OmniOS